The present invention relates to a case locking mechanism that is used in a case having two openable case parts, such as the case of an air cleaner connected to the intake system of a vehicle engine, and holds the case parts in a closed state.
Conventionally, as a locking mechanism for holding this sort of case in a closed state, one type is known in which metal clamp member is attached to one of the case parts. The clamp member is hooked to the other case part, so that the two case parts are held in a closed state. This conventional holding mechanism requires a metal member used as the clamp member, which is prepared separately from the case parts. This can complicates the structure of the mechanism.
In order to eliminate such a drawback, for example, Japanese Laid-Open Patent Publication Nos. 2005-23860 and 2005-337064 each disclose a structure in which a member that corresponds to the clamp member is integrally formed with case parts.
In the structure disclosed in Japanese Laid-Open Patent Publication No. 2005-23860, a synthetic resin cover body is pivotally attached with a hinge to a synthetic resin case body. The cover body pivots relative to the case body, so that the cover body and the case body are selectively opened and closed. A holding mechanism is provided between the open ends of the case body and the cover body. The holding mechanism holds the cover body in a closed state with respect to the case body. Specifically, an elongated insertion hole extending vertically is formed on an outer side surface of the case body, and a pair of hook claws corresponding to the insertion holes are formed on an outer side surface of the cover body. Each hook claw has at its distal end a claw portion that can be inserted into the insertion hole. The hook claws are each formed integrally with the cover body with a linear elastically deformable piece in between. The deformable pieces are formed to be elastically deformable along a direction parallel with the outer side surface of the cover body.
When the cover body is pivoted from an open position to a closed position with respect to the case body, a distal guide surface formed at the claw portion of each hook claw is engaged with the open edge of the entrance of the insertion hole. This engagement elastically deforms the deformable pieces, so that a pair of the hook claws are inserted in the insertion hole while approaching each other along a direction parallel with the outer side surface of the cover body. When the claw portions of the hook claws reach the exit of the insertion hole, the deformable pieces are restored from the elastically deformed state, so that the claw portions of the hook claws are hooked to the open edge of the exit of the insertion hole. Accordingly, the cover body is held at the closed position with respect to the case body.
In the structure disclosed in Japanese Laid-Open Patent Publication No. 2005-337064, a synthetic resin upper case is detachably attached to a synthetic resin lower case. A plurality of holding mechanisms for holding the upper case in a closed state with respect to the lower case are provided between the open ends of the lower case and the upper case. Each holding mechanism has a pair of hook portions formed on an outer side surface of the lower case. The hook portions have an L-shaped cross section and an inverted L-shaped transverse cross section, respectively. The hook portions are provided on and protrude from an outer side surface of the lower case with predetermined space therebetween. A pair of grooves are formed between each hook portion and an outer side surface of the lower case. A pair of hook claws, which correspond to the grooves, are formed on an outer side surface of the upper case. Each hook claw has at its distal end a claw portion that can be inserted into the grooves of the hook portion. The hook claws are each formed integrally with the upper case with a linear elastically deformable piece. The deformable pieces are formed to be elastically deformable along a direction parallel with the outer side surface of the upper case.
When the upper case is attached to and covers the lower case, a distal guide surface formed at the claw portion of each hook claw is engaged with the upper edge of the corresponding hook portion. This engagement elastically deforms the deformable pieces, so that a pair of the hook claws are inserted in the grooves of the hook portions while approaching each other along a direction parallel with the outer side surface of the upper case. When the claw portions of the hook claws reach the lower ends of the grooves, the deformable pieces are restored from the elastically deformed state, so that the claw portions of the hook claws are hooked to the lower edges of the hook portions. Accordingly, the upper case is held at the closed position with respect to the lower body.
In the conventional case locking mechanisms of the above described patent documents, the hook claws are integrally formed with the case part with a linear elastically deformable pieces in between. When the deformable pieces are elastically deformed in a direction parallel with the outer side surface of the case part, the claw portions of the hook claws are hooked to or unhooked from the open edge of the insertion hole or the edge of the hook portion. If such a structure is employed, the deformable pieces need to be greatly deformed to allow the hook claws to be hooked to and unhooked from the insertion hole or the hook portion. However, since the linear elastically deformable pieces are hard to be deformed, one of the case parts needs to be pressed toward the other case part with a great force when the case parts are closed. When the case parts are opened, the hook claws need to be deformed from the hooked position to the unhooked position with a great force against the elastic force of the deformable pieces. Therefore, the case parts are hard to close and open.